JP4196527B2 - Liquid crystal display element - Google Patents

Liquid crystal display element Download PDF

Info

Publication number
JP4196527B2
JP4196527B2 JP2000237724A JP2000237724A JP4196527B2 JP 4196527 B2 JP4196527 B2 JP 4196527B2 JP 2000237724 A JP2000237724 A JP 2000237724A JP 2000237724 A JP2000237724 A JP 2000237724A JP 4196527 B2 JP4196527 B2 JP 4196527B2
Authority
JP
Japan
Prior art keywords
liquid crystal
display element
crystal display
substrates
alignment film
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP2000237724A
Other languages
Japanese (ja)
Other versions
JP2002023168A (en
Inventor
聡史 久光
昌二 小谷
健 北洞
秀昭 植田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Konica Minolta Inc
Original Assignee
Konica Minolta Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Konica Minolta Inc filed Critical Konica Minolta Inc
Priority to JP2000237724A priority Critical patent/JP4196527B2/en
Priority to US09/887,654 priority patent/US6699534B2/en
Publication of JP2002023168A publication Critical patent/JP2002023168A/en
Application granted granted Critical
Publication of JP4196527B2 publication Critical patent/JP4196527B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133711—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by organic films, e.g. polymeric films
    • G02F1/133723—Polyimide, polyamide-imide
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/13718—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on a change of the texture state of a cholesteric liquid crystal
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K2323/00—Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
    • C09K2323/02—Alignment layer characterised by chemical composition
    • C09K2323/027—Polyimide
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133711—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by organic films, e.g. polymeric films
    • G02F1/133726—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by organic films, e.g. polymeric films made of a mesogenic material
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133765—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers without a surface treatment
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1347—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
    • G02F1/13471—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells
    • G02F1/13473—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells for wavelength filtering or for colour display without the use of colour mosaic filters

Landscapes

  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Mathematical Physics (AREA)
  • Liquid Crystal (AREA)
  • Liquid Crystal Substances (AREA)
  • Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は液晶表示素子に関する。
【０００２】
【従来の技術】
近年、ネマティック液晶にカイラル材料を添加することにより、室温においてコレステリック相を示すようにしたカイラルネマティック液晶などのコレステリック相を示す液晶を用いた液晶表示素子が種々研究されている。
【０００３】
かかる液晶表示素子は、通常一対の基板間にコレステリック相を示す液晶を含む液晶層が挟持されており、例えば、コレステリック相を示す液晶の選択反射を利用した反射型の液晶表示素子として用いられる。この反射型の液晶表示素子では高低の電圧印加により液晶をプレーナ状態（着色状態）とフォーカルコニック状態（消色状態）に切り替えて表示を行う。
【０００４】
また、この液晶表示素子には液晶分子の配向を制御するために配向膜が設けられることがある。
【０００５】
【発明が解決しようとする課題】
しかしながら、これまでのコレステリック相を示す液晶を使用した反射型の液晶表示素子においては、配向膜が設けられる場合、液晶と配向膜の相互作用が弱いと液晶分子に均一に配向効果を及ぼすことができず、画像表示において、フォーカルコニック状態での散乱が多くなり十分なコントラストを得難い。
【０００６】
そこで本発明は、一対の基板間にコレステリック相を示す液晶を含む液晶層が挟持された液晶表示素子であって、前記液晶における液晶分子に均一に配向効果を及ぼすことができ、これにより画像表示におけるコントラストを向上させることができる液晶表示素子を提供することを課題とする。
【０００７】
また本発明は、一対の基板間にコレステリック相を示す液晶を含む液晶層が挟持された液晶表示素子であって、視角依存性を少なくすることができる液晶表示素子を提供することを課題とする。
【０００８】
【課題を解決するための手段】
本発明者は前記課題を解決するため研究を重ねたところ、少なくとも一方に配向膜を有する一対の基板間にコレステリック相を示す液晶を含む液晶層が挟持された液晶表示素子においては、前記配向膜中に前記液晶における液晶分子との分子間相互作用をもつ置換基であるメソゲン基を導入することで、該液晶と該配向膜の相互作用が強くなって液晶分子に均一に配向効果を及ぼすことができ、フォーカルコニック状態での散乱が少なくなり、画像表示におけるコントラストが向上することを見出した。また、該配向膜をラビング処理しないことで視角依存性を少なくすることができることも見出した。
【０００９】
本発明はかかる知見に基づくものであり、前記課題を解決するため、少なくとも一方に配向膜を有する一対の基板間にコレステリック相を示す液晶を含む液晶層が挟持された液晶表示素子であり、
前記配向膜が構造中にメソゲン基を有するポリイミドからなり、且つ、ラビング処理されていないことを特徴とする液晶表示素子を提供する。
【００１０】
本発明にいうメソゲン基とは、分子が液晶性を示すのに必要な剛直構造の置換基をいう。このメソゲン基としては、例えば、コレステロール基、ビフェニル基、フェニルベンゾエート基などを挙げることができる。
【００１１】
本発明に係る液晶表示素子は、コレステリックを示す液晶の選択反射を利用した反射型の液晶表示素子として用いることができる。
【００１２】
本発明の液晶表示素子では、反射型の液晶表示素子として用いる場合、高低の電圧印加により液晶をプレーナ状態（着色状態）とフォーカルコニック状態（消色状態）に切り替えて表示を行う。
【００１３】
本発明に係る液晶表示素子によると、前記配向膜が構造中にメソゲン基を有するポリイミドからなるので、前記液晶と前記配向膜の相互作用が強くなり、前記液晶における液晶分子に均一に配向効果を及ぼすことができ、それだけ画像表示におけるコントラストを向上させることができる。また、前記配向膜がラビング処理されていないので、視角依存性を少なくすることができる。
【００１４】
前記メソゲン基として次のものを例示できる。
（ａ）ステロイド骨格、ビフェニル骨格及びフェニルシクロヘキサン骨格のうちのいずれかを含むメソゲン基。
（ｂ）ポリイミドを形成するジアミン化合物の側鎖。
（ｃ）前記（ａ）、（ｂ）を組み合わせたもの。
【００１５】
前記配向膜原料を合成する化合物の化学構造式を（１）〜（５）に示す。
【００１６】
【化１】

Figure 0004196527
【００１７】
前記配向膜として、例えば、次の膜を挙げることができる。すなわち、
（ａ）化学構造式（１）、（２）、（３）で示される化合物から合成される、構造中にステロイド骨格を含むメソゲン基を有するポリイミドからなる膜。
（ｂ）化学構造式（１）、（２）、（４）で示される化合物から合成される、構造中にビフェニル骨格を含むメソゲン基を有するポリイミドからなる膜。
（ｃ）化学構造式（１）、（２）、（５）で示される化合物から合成される、構造中にフェニルシクロヘキサン骨格を含むメソゲン基を有するポリイミドからなる膜。
【００１８】
いずれにしても、前記コレステリック相を示す液晶はネマティック液晶にカイラル材を添加したカイラルネマティック液晶であってもよい。この場合、前記カイラル材の含有量としては、例えば７重量（ｗｔ）％〜５０重量（ｗｔ）％程度が好ましい。
【００１９】
前記コレステリック相を示す液晶として、ネマティック液晶にカイラル材を添加したカイラルネマティック液晶を用いる場合、このカイラルネマティック液晶は、添加するカイラルドーパント（カイラル材）の量を変えることにより、選択反射波長を制御することができるという利点がある。カイラル材の添加量が少なすぎると十分なメモリー性（すなわち、電圧印加をやめた後の、プレーナ状態であった領域のプレーナ状態の保持性、或いはフォーカルコニック状態であった領域のフォーカルコニック状態の保持性）を得られないことがあり、多すぎると室温でコレステリック相を示さなくなったり、固化したりすることがある。
【００２０】
いずれにしても、前記配向膜は膜厚が薄すぎると液晶分子の配向を制御ができないことがあり、厚すぎると駆動電圧の上昇を招く。例えば、前記配向膜の膜厚としては１００Å〜２０００Å程度が好ましい。
【００２１】
本発明に係る液晶表示素子は、これを少なくとも２層積層して積層型液晶表示素子とすることもできる。この場合、少なくとも２層の液晶表示素子として、互いに異なる色表示を行う液晶表示素子を用いることで、２色以上のカラー表示を行うことができる。なお、青色表示を行う液晶表示素子、緑色表示を行う液晶表示素子、赤色表示を行う液晶表示素子の少なくとも三つの液晶表示素子を採用するとフルカラー表示を行うことができる。
【００２２】
いずれにしても、かかる積層型液晶表示素子においては、隣り合う液晶表示素子において、その両者間の基板を共通にしてもよい。
【００２３】
【発明の実施の形態】
以下、本発明の実施の形態について図面を参照して説明する。
【００２４】
図１は本発明に係る液晶表示素子の１例の概略断面図である。また、図２は本発明に係る液晶表示素子の他の例であり、青色表示を行う液晶層、緑色表示を行う液晶層、赤色表示を行う液晶層の３層の液晶層を含む積層型液晶表示素子の概略断面図である。なお、図１及び図２の液晶表示素子において、基本的に同じ構成、作用を有する箇所については同じ参照符号を付してある。
【００２５】
図１に示す液晶表示素子は、一対の基板１、２間にコレステリック相を示す液晶６を含む液晶層１０が挟持されいる。また、図２に示す液晶表示素子は、一対の基板１、２間に、コレステリック相を示す液晶６ｂを含む青色表示を行う液晶層１０ｂ、コレステリック相を示す液晶６ｇを含む緑色表示を行う液晶層１０ｇ、コレステリック相を示す液晶６ｒを含む赤色表示を行う液晶層１０ｒがそれぞれ挟持されいる。
【００２６】
基板１、２を含め、本発明の液晶表示素子に用いることができる一対の基板は、少なくとも一方が透光性を有していることが必要である。また、光を入射させる側とは反対側の基板の外面（裏面）には、必要に応じて、可視光吸収層が設けられる。ここでは基板１、２はいずれも透光性を有しており、図１の例では基板２の裏面（外面）に、図２の例では液晶層１０ｒを挟持している外側の基板２の裏面（外面）に黒色の光吸収層３が設けられている。
【００２７】
透光性を有する基板としては、ガラス基板を例示できる。このガラス基板以外に、高分子樹脂からなる基板、例えば、ポリカーボネート、ポリエーテルスルホン、ポリエチレンテレフタレート、ポリアリレート等のフレキシブルな樹脂基板等も使用可能である。
【００２８】
基板１、２は、それぞれ透明電極１１、１２を有している。透明電極１１、１２は、ここではＩＴＯからなっている。
【００２９】
図１及び図２に示す液晶表示素子においては、透明基板１、２の表面にそれぞれ間隔おいて平行に並んだ複数の帯状の透明電極１１、１２が形成されており、両基板１、２は、透明電極１１、１２の向きが互いに直角方向となるように対向させてあり、透明電極１１、１２が重なり合う領域が表示画素となる。
【００３０】
図１及び図２に示す液晶表示素子を含め、本発明の液晶表示素子において、基板表面には必要に応じて、電極間の短絡を防止したり、ガスバリア層として液晶の信頼性を向上させる機能を有する絶縁膜を設けることができる。図１及び図２の液晶表示素子では、透明電極１１、１２上に絶縁膜７がそれぞれ設けられている。絶縁膜７上には配向膜８が設けられている。配向膜８は構造中にメソゲン基を有するポリイミドからなり、且つ、ラビング処理されていない。なお、配向膜８は、ここでは一対の基板１、２のそれぞれに設けられているが、一対の基板１、２のうち少なくとも一方に設けられていればよい。
【００３１】
図１及び図２に示す液晶表示素子を含め、本発明の液晶表示素子には液晶が漏れないように素子の周囲をシールするシール材を設けることができる。図示例の基板１、２間には、表示領域外である基板１、２の周縁部に液晶６、６ｒ、６ｇ、６ｂを封じ込めるためのシール材Ｓが設けられている。
【００３２】
シール材としては、例えば、エポキシ樹脂、アクリル樹脂等の熱硬化型或いは光硬化型接着剤が使用可能である。
【００３３】
図１及び図２に示す液晶表示素子を含め、本発明の液晶表示素子は、一対の基板間に、該基板間のギャップを均一に保持するためのスペーサが設けられていてもよい。図１及び図２に示す液晶表示素子は、基板１，２間にスペーサ５を配置してある。このスペーサとしては、樹脂製又は無機酸化物製の球体を例示できる。
【００３４】
図１及び図２に示す液晶表示素子を含め、本発明の液晶表示素子は、強い自己保形性を付与するために、一対の基板間が複数の樹脂構造物で支持されていてもよい。本例の液晶表示素子には、図１及び図２に示すように基板１、２間の表示領域内に柱状構造物４が設けられている。
【００３５】
図３は樹脂構造物４の配置状態例を示す図である。図３に示すように、表示領域内の樹脂構造物４は、例えば、格子配列などの所定の配置規則に基づいて、一定の間隔をおいて配列された、円柱状、断面四角柱状、断面楕円柱状などのドット状のものとすることができる。
【００３６】
図１の液晶表示素子では、所定の電圧印加によって液晶６の各画素領域においてプレーナ状態（着色状態）とフォーカルコニック状態（消色状態、黒色表示状態）とに切り替えて表示を行う。
【００３７】
また、図２の液晶表示素子では、所定の電圧印加によって液晶６ｒ、６ｇ、６ｂの各画素領域において着色状態と消色状態とに切り替えて表示を行う。なお、図２の液晶表示素子において、液晶６ｒ、６ｇ、６ｂをいずれも着色状態にすると白色表示となり、いずれも消色状態にすると黒色表示となる。
【００３８】
以上説明した液晶表示素子によると、配向膜８が構造中にメソゲン基を有するポリイミドからなるので、液晶６、６ｂ、６ｇ、６ｒと配向膜８の相互作用が強くなり、液晶６、６ｂ、６ｇ、６ｒにおける液晶分子に対して均一に配向効果を及ぼすことができ、それだけ画像表示におけるコントラストを向上させることができる。また、配向膜８がラビング処理されていないので、視角依存性を少なくすることができる。
【００３９】
次に本発明に係る液晶表示素子の性能評価実験を行ったので、比較実験とともに以下に説明する。
【００４０】
以下の各実験例において、Δｎは屈折率異方性、Δεは誘電率異方性、ＴＮ−Ｉは等方相転移温度である。また、コントラストの測定はＹ値（視感反射率）を測定することで行った。Ｙ値の測定は、白色光源を有する分光測色計ＣＭ３７００ｄ（ミノルタ社製）を用いて行った。
【００４１】
なお、コントラストは（高反射率状態でのＹ値／低反射率状態でのＹ値）で与えられる。以下に説明する各実験例における液晶表示素子においては、液晶表示素子を着色状態としたときに高反射率状態となり、消色状態としたときに低反射率状態となる。
（実験例１）
ネマティック液晶混合物Ｂ（Δｎ＝０．２１０、Δε＝３８．７、ＴＮ−Ｉ＝１１９℃）に対して、カイラル材料Ｓ−８１１（メルク社製）を２６ｗｔ％添加した液晶組成物Ｂ１を調製した。液晶組成物Ｂ１は５６０ｎｍ付近の波長の光を選択反射するように調製されている。
【００４２】
一方の基板として、透明電極が設けられたガラス基板を用意し、該ガラス基板に設けられた透明電極上に前記化学構造式（１）、（２）、（３）で示される化合物から合成される、構造中にメソゲン基を有するポリイミドからなる配向膜を８００Åの厚みで形成した。
【００４３】
また、もう一方の基板として、透明電極が設けられたガラス基板を用意し、該ガラス基板上の透明電極上には、まず厚み２０００Åの絶縁膜ＨＩＭ３０００（日立化成社製）を形成した後、さらにその上に前記化学構造式（１）、（２）、（３）で示される化合物から合成される、構造中にメソゲン基を有するポリイミドからなる配向膜を８００Åの厚みで形成した。
【００４４】
続いて、一方の基板上の周縁部にシール材ＸＮ２１Ｓ（三井化学社製）をスクリーン印刷して所定高さの壁を形成した。
【００４５】
両基板を対向させ、基板間に７μｍ径のスペーサ（積水ファインケミカル社製）を挟んでセルギャップを調整し、前記の液晶組成物Ｂ１を挟持し、これを液晶表示素子とした。
【００４６】
この液晶表示素子の光を入射させる側とは反対側の基板の外面（裏面）に黒色の光吸収体を設けた。
【００４７】
本液晶表示素子を着色状態と消色状態にするために所定電圧（着色時６５Ｖ、５ｍｓ、消色時４０Ｖ、５ｍｓ）で駆動したところ、緑色表示時のＹ値は２２．４、黒色表示時のＹ値は２．６、コントラストは８．６：１であり、着色・黒色表示特性共に良好で、特に黒色表示特性が良好なためコントラストの高い液晶表示素子となった。
（実験例２）
ネマティック液晶混合物Ａ（Δｎ＝０．２１２、Δε＝４４、ＴＮ−Ｉ＝１０３℃）、ネマティック液晶混合物Ｂ（Δｎ＝０．２１０、Δε＝３８．７、ＴＮ−Ｉ＝１１９℃）、ネマティック液晶混合物Ｃ（Δｎ＝０．２１４、Δε＝７．６、ＴＮ−Ｉ＝１４３℃）に対して、それぞれにカイラル材料Ｓ−８１１（メルク社製）を所定量、すなわち２１ｗｔ％、２６ｗｔ％、３６ｗｔ％添加した液晶組成物Ａ１、Ｂ１、Ｃ１を調製した。液晶組成物Ａ１は６８０ｎｍ付近の、液晶組成物Ｂ１は５６０ｎｍ付近の、液晶組成物Ｃ１は４８０ｎｍ付近の波長の光を選択反射するように調製されている。
【００４８】
次に、一方の基板として、透明電極が設けられた三つのポリカーボネート（ＰＣ）からなるフィルム基板を用意し、該各ＰＣフィルム基板に設けられた透明電極上に前記化学構造式（１）、（２）、（３）で示される化合物から合成される、構造中にメソゲン基を有するポリイミドからなる配向膜を５００Åの厚みでそれぞれ形成し、その上に９μｍ、７μｍ、５μｍ径のスペーサ（積水ファインケミカル社製）をそれぞれ散布した。
【００４９】
また、もう一方に基板として、透明電極が設けられた三つのＰＣフィルム基板を用意し、該各ＰＣフィルム基板上の透明電極上には、まず厚み２０００Åの絶縁膜ＨＩＭ３０００（日立化成社製）をそれぞれ形成した後、その上に前記化学構造式（１）、（２）、（３）で示される化合物から合成される、構造中にメソゲン基を有するポリイミドからなる配向膜を５００Åの厚みでそれぞれ形成形成した。
【００５０】
続いて、一方の各基板上の周縁部にシール材ＸＮ２１Ｓ（三井化学社製）をスクリーン印刷して所定高さの壁をそれぞれ形成した。
【００５１】
その後該一方の各基板上にシール材の高さとシール材に囲まれた部分の面積から計算された量の液晶組成物Ａ１、Ｂ１、Ｃ１をそれぞれ塗布し、それぞれ２枚の基板を電極形成面が対向するように重ね合わせ、この基板対の両側から加圧しながら加熱した。加圧および加熱は、例えば、図４に示す貼り合わせ装置を用いて平板（図中９１）上に一方の基板（図中１）を載せ、これにもう一方の基板（図中２）を重ね、端部から加熱・加圧ローラ（図中９２）により加熱・加圧しながら、ローラ９２と平板９１との間に相対的に通過させることにより行なうことができる。なお、図４においてＳ及び５はそれぞれシール壁及びスペーサである。こうしてそれぞれ２枚の基板を貼り合わせ、１５０℃で１時間加熱し、液晶セルａ１、ｂ１、ｃ１を作製した。
【００５２】
これら３種類の液晶セルをａ１、ｂ１、ｃ１の順に積層し、これを液晶表示素子とした。この液晶表示素子の裏面（液晶セルａ１の外面（裏面））には黒色の光吸収膜を設けた。
【００５３】
各液晶セルを着色状態と消色状態にするために所定電圧（着色時：ａ１には６０Ｖ ５ｍｓ、ｂ１には６５Ｖ ５ｍｓ、ｃ１には７５Ｖ ５ｍｓ、消色時：ａ１には４０Ｖ ５ｍｓ、ｂ１には４０Ｖ ５ｍｓ、ｃ１には５０Ｖ ５ｍｓ）でそれぞれ駆動したところ、液晶表示素子の白色表示時のＹ値は２８．５、黒色表示時のＹ値は４．３、液晶表示素子のコントラストは６．６：１（Ｗ（白色）／Ｂ（黒色））であり、白色・黒色表示特性共に良好で、特に黒色表示特性が良好なためコントラストの高い液晶表示素子となった。
（実験例３）
ネマティック液晶混合物Ａ（Δｎ＝０．２１２、Δε＝４４、ＴＮ−Ｉ＝１０３℃）、ネマティック液晶混合物Ｂ（Δｎ＝０．２１０、Δε＝３８．７、ＴＮ−Ｉ＝１１９℃）、ネマティック液晶混合物Ｃ（Δｎ＝０．２１４、Δε＝７．６、ＴＮ−Ｉ＝１４３℃）に対して、それぞれにカイラル材料Ｓ−８１１（メルク社製）を所定量、すなわち２１ｗｔ％、２６ｗｔ％、３６ｗｔ％添加した液晶組成物Ａ１、Ｂ１、Ｃ１を調製した。液晶組成物Ａ１は６８０ｎｍ付近の、液晶組成物Ｂ１は５６０ｎｍ付近の、液晶組成物Ｃ１は４８０ｎｍ付近の波長の光を選択反射するように調製されている。
【００５４】
次に、一方の基板として、透明電極が設けられた三つのポリカーボネート（ＰＣ）からなるフィルム基板を用意し、該各ＰＣフィルム基板に設けられた透明電極上に前記化学構造式（１）、（２）、（４）で示される化合物から合成される、構造中にメソゲン基を有するポリイミドからなる配向膜を８００Åの厚みでそれぞれ形成し、その上に９μｍ、７μｍ、５μｍ径のスペーサ（積水ファインケミカル社製）をそれぞれ散布した。
【００５５】
また、もう一方に基板として、透明電極が設けられた三つのＰＣフィルム基板を用意し、該各ＰＣフィルム基板上の透明電極上には、まず厚み２０００Åの絶縁膜ＨＩＭ３０００（日立化成社製）をそれぞれ形成した後、その上に前記化学構造式（１）、（２）、（４）で示される化合物から合成される、構造中にメソゲン基を有するポリイミドからなる配向膜を８００Åの厚みでそれぞれ形成した。
【００５６】
続いて、一方の各基板上の周縁部にシール材ＸＮ２１Ｓ（三井化学社製）をスクリーン印刷して所定高さの壁をそれぞれ形成した。
【００５７】
その後該一方の各基板上にシール材の高さとシール材に囲まれた部分の面積から計算された量の液晶組成物Ａ１、Ｂ１、Ｃ１をそれぞれ塗布し、実験例２と同様にして貼り合わせ装置を用いてそれぞれ２枚の基板を貼り合わせ、１５０℃で１時間加熱し、液晶セルａ１、ｂ１、ｃ１を作製した。
【００５８】
これら３種類の液晶セルをａ１、ｂ１、ｃ１の順に積層し、これを液晶表示素子とした。この液晶表示素子の裏面（液晶セルａ１の外面（裏面））には黒色の光吸収膜を設けた。
【００５９】
各液晶セルを着色状態と消色状態にするために所定電圧（着色時：ａ１には６０Ｖ ５ｍｓ、ｂ１には６５Ｖ ５ｍｓ、ｃ１には７５Ｖ ５ｍｓ、消色時：ａ１には４０Ｖ ５ｍｓ、ｂ１には４０Ｖ ５ｍｓ、ｃ１には５０Ｖ ５ｍｓ）でそれぞれ駆動したところ、液晶表示素子の白表示時のＹ値は２８．８、黒表示時のＹ値は４．８、コントラストは６．０：１（Ｗ／Ｂ）であり、白・黒表示特性共に良好で、特に黒表示特性が良好なためコントラストの高い液晶表示素子となった。
（実験例４）
ネマティック液晶混合物Ｄ（Δｎ＝０．２０４、Δε＝７．４、ＴＮ−Ｉ＝９１．７℃）に対して、それぞれにカイラル材料Ｓ−８１１（メルク社製）を所定量、すなわち２２ｗｔ％、２８ｗｔ％、４８ｗｔ％添加した液晶組成物Ｄ１、Ｄ２、Ｄ３を調製した。液晶組成物Ｄ１は６８０ｎｍ付近の、液晶組成物Ｄ２は５６０付近の、液晶組成物Ｄ３は４８０ｎｍ付近の波長の光を選択反射するように調製されている。
【００６０】
次に、一方の基板として、透明電極が設けられた三つのポリカーボネート（ＰＣ）からなるフィルム基板を用意し、該各ＰＣフィルム基板に設けられた透明電極上に前記化学構造式（１）、（２）、（３）で示される化合物から合成されるポリイミドからなる、構造中にメソゲン基を有する配向膜を１０００Åの厚みでそれぞれ形成し、その上に９μｍ、７μｍ、５μｍ径のスペーサ（積水ファインケミカル社製）をそれぞれ散布した。
【００６１】
また、もう一方に基板として、透明電極が設けられた三つのＰＣフィルム基板を用意し、該各ＰＣフィルム基板上の透明電極上には、まず厚み２０００Åの絶縁膜ＨＩＭ３０００（日立化成社製）をそれぞれ形成した後、その上に前記化学構造式（１）、（２）、（３）で示される化合物から合成される、構造中にメソゲン基を有するポリイミドからなる配向膜を１０００Åの厚みでそれぞれ形成した。
【００６２】
続いて、一方の各基板上の周縁部にシール材ＸＮ２１Ｓ（三井化学社製）をスクリーン印刷して所定高さの壁をそれぞれ形成した。
【００６３】
その後該一方の各基板上にシール材の高さとシール材に囲まれた部分の面積から計算された量の液晶組成物Ｄ１、Ｄ２、Ｄ３をそれぞれ塗布し、実験例２と同様にして貼り合わせ装置を用いてそれぞれ２枚の基板を貼り合わせ、１５０℃で１時間加熱し、液晶セルｄ１、ｄ２、ｄ３を作製した。
【００６４】
これら３種類の液晶セルをｄ１、ｄ２、ｄ３の順に積層し、これを液晶表示素子とした。この液晶表示素子の裏面（液晶セルｄ１の外面（裏面））には黒色の光吸収膜を設けた。
【００６５】
各液晶セルを着色状態と消色状態にするために所定電圧（着色時：ｄ１には１０５Ｖ ５ｍｓ、ｄ２には８５Ｖ ５ｍｓ、ｄ３には６０Ｖ ５ｍｓ、消色時：ｄ１には６０Ｖ ５ｍｓ、ｄ２には５０Ｖ ５ｍｓ、ｄ３には３５Ｖ ５ｍｓ）でそれぞれ駆動したところ、液晶表示素子の白表示時のＹ値は２７．９、黒表示時のＹ値は４．４、コントラストは６．３：１（Ｗ／Ｂ）であり、白・黒表示特性共に良好で、特に黒表示特性が良好なためコントラストの高い液晶表示素子となった。
（実験例５）
ネマティック液晶混合物Ｄ（Δｎ＝０．２０４、Δε＝７．４、ＴＮ−Ｉ＝９１．７℃）に対して、それぞれにカイラル材料Ｓ−８１１（メルク社製）を所定量、すなわち２２ｗｔ％、２８ｗｔ％、４８ｗｔ％添加した液晶組成物Ｄ１、Ｄ２、Ｄ３を調製した。液晶組成物Ｄ１は６８０ｎｍ付近の、液晶組成物Ｄ２は５６０付近の、液晶組成物Ｄ３は４８０ｎｍ付近の波長の光を選択反射するように調製されている。
【００６６】
次に、一方の基板として、透明電極が設けられた三つのポリカーボネート（ＰＣ）からなるフィルム基板を用意し、該各ＰＣフィルム基板に設けられた透明電極上に前記化学構造式（１）、（２）、（５）で示される化合物から合成されるポリイミドからなる、構造中にメソゲン基を有する配向膜を３００Åの厚みでそれぞれ形成し、その上に９μｍ、７μｍ、５μｍ径のスペーサ（積水ファインケミカル社製）をそれぞれ散布した。
【００６７】
また、もう一方に基板として、透明電極が設けられた三つのＰＣフィルム基板を用意し、該各ＰＣフィルム基板上の透明電極上には、まず厚み２０００Åの絶縁膜ＨＩＭ３０００（日立化成社製）をそれぞれ形成した後、その上に前記化学構造式（１）、（２）、（５）で示される化合物から合成されるポリイミドからなる、構造中にメソゲン基を有する配向膜を３００Åの厚みでそれぞれ形成した。
【００６８】
続いて、一方の各基板上の周縁部にシール材ＸＮ２１Ｓ（三井化学社製）をスクリーン印刷して所定高さの壁をそれぞれ形成した。
【００６９】
その後該一方の各基板上にシール材の高さとシール材に囲まれた部分の面積から計算された量の液晶組成物Ｄ１、Ｄ２、Ｄ３をそれぞれ塗布し、実験例２と同様にして貼り合わせ装置を用いてそれぞれ２枚の基板を貼り合わせ、１５０℃で１時間加熱し、液晶セルｄ１、ｄ２、ｄ３を作製した。
【００７０】
これら３種類の液晶セルをＤ１、Ｄ２、Ｄ３の順に積層し、これを液晶表示素子とした。この液晶表示素子の裏面（液晶セルｄ１の外面（裏面））には黒色の光吸収膜を設けた。
【００７１】
各液晶セルを着色状態と消色状態にするために所定電圧（着色時：ｄ１には１０５Ｖ ５ｍｓ、ｄ２には８５Ｖ ５ｍｓ、ｄ３には６０Ｖ ５ｍｓ、消色時：ｄ１には６０Ｖ ５ｍｓ、ｄ２には５０Ｖ ５ｍｓ、ｄ３には３５Ｖ ５ｍｓ）でそれぞれ駆動したところ、液晶表示素子の白表示時のＹ値は２７．４、黒表示時のＹ値は４．７、コントラストは５．８：１（Ｗ／Ｂ）であり、白・黒表示特性共に良好で、特に黒表示特性が良好なためコントラストの高い液晶表示素子となった。
（比較実験例１）
ネマティック液晶混合物Ｂ（Δｎ＝０．２１０、Δε＝３８．７、ＴＮ−Ｉ＝１１９℃）に対して、カイラル材料Ｓ−８１１（メルク社製）を２６ｗｔ％添加した液晶組成物Ｂ１を調製した。液晶組成物Ｂ１は５６０ｎｍ付近の波長の光を選択反射するように調製されている。
【００７２】
一方の基板として、透明電極が設けられたガラス基板を用意し、該ガラス基板に設けられた透明電極上に前記化学構造式（１）、（２）で示される化合物から合成されるポリイミドからなる配向膜を８００Åの厚みで形成した。
【００７３】
また、もう一方の基板として、透明電極が設けられたガラス基板を用意し、該ガラス基板上の透明電極上には、まず厚み２０００Åの絶縁膜ＨＩＭ３０００（日立化成社製）を形成した後、さらにその上に前記化学構造式（１）、（２）で示される化合物から合成されるポリイミドからなる配向膜を８００Åの厚みで形成した。
【００７４】
続いて、一方の基板上の周縁部にシール材ＸＮ２１Ｓ（三井化学社製）をスクリーン印刷して所定高さの壁を形成した。
【００７５】
両基板を対向させ、基板間に７μｍ径のスペーサ（積水ファインケミカル社製）を挟んでセルギャップを調整し、前記の液晶組成物Ｂ１を挟持し、これを液晶表示素子とした。
【００７６】
この液晶表示素子の光を入射させる側とは反対側の基板の外面（裏面）に黒色の光吸収体を設けた。
【００７７】
本液晶表示素子を着色状態と消色状態にするために所定電圧（着色時６５Ｖ、５ｍｓ、消色時４０Ｖ、５ｍｓ）で駆動したところ、緑色表示時のＹ値は２２．６、黒色表示時のＹ値は３．８、コントラストは５．９：１であり、特に黒色表示特性が悪いためコントラストの低い液晶表示素子となってしまった。
（比較実験例２）
ネマティック液晶混合物Ａ（Δｎ＝０．２１２、Δε＝４４、ＴＮ−Ｉ＝１０３℃）、ネマティック液晶混合物Ｂ（Δｎ＝０．２１０、Δε＝３８．７、ＴＮ−Ｉ＝１１９℃）、ネマティック液晶混合物Ｃ（Δｎ＝０．２１４、Δε＝７．６、ＴＮ−Ｉ＝１４３℃）に対して、それぞれにカイラル材料Ｓ−８１１（メルク社製）を所定量、すなわち２１ｗｔ％、２６ｗｔ％、３６ｗｔ％添加した液晶組成物Ａ１、Ｂ１、Ｃ１を調製した。液晶組成物Ａ１は６８０ｎｍ付近の、液晶組成物Ｂ１は５６０ｎｍ付近の、液晶組成物Ｃ１は４８０ｎｍ付近の波長の光を選択反射するように調製されている。
【００７８】
次に、一方の基板として、透明電極が設けられた三つのポリカーボネート（ＰＣ）からなるフィルム基板を用意し、該各ＰＣフィルム基板に設けられた透明電極上に前記化学構造式（１）、（２）で示される化合物から合成されるポリイミドからなる配向膜を８００Åの厚みで形成し、その上に９μｍ、７μｍ、５μｍ径のスペーサ（積水ファインケミカル社製）をそれぞれ散布した。
【００７９】
また、もう一方に基板として、透明電極が設けられた三つのＰＣフィルム基板を用意し、該各ＰＣフィルム基板上の透明電極上には、まず厚み２０００Åの絶縁膜ＨＩＭ３０００（日立化成社製）をそれぞれ形成した後、その上に前記化学構造式（１）、（２）で示される化合物から合成されるポリイミドからなる配向膜を８００Åの厚みでそれぞれ形成した。
【００８０】
続いて、一方の各基板上の周縁部にシール材ＸＮ２１Ｓ（三井化学社製）をスクリーン印刷して所定高さの壁をそれぞれ形成した。
【００８１】
その後該一方の各基板上にシール材の高さとシール材に囲まれた部分の面積から計算された量の液晶組成物Ａ１、Ｂ１、Ｃ１をそれぞれ塗布し、実験例２と同様にして貼り合わせ装置を用いてそれぞれ２枚の基板を貼り合わせ、１５０℃で１時間加熱し、液晶セルａ１、ｂ１、ｃ１を作製した。
【００８２】
これら３種類の液晶セルをａ１、ｂ１、ｃ１の順に積層し、これを液晶表示素子とした。この液晶表示素子の裏面（液晶セルａ１の外面（裏面））には黒色の光吸収膜を設けた。
【００８３】
各液晶セルを着色状態と消色状態にするために所定電圧（着色時：ａ１には６０Ｖ ５ｍｓ、ｂ１には６５Ｖ ５ｍｓ、ｃ１には７５Ｖ ５ｍｓ、消色時：ａ１には４０Ｖ ５ｍｓ、ｂ１には４０Ｖ ５ｍｓ、ｃ１には５０Ｖ ５ｍｓ）でそれぞれ駆動したところ、液晶表示素子の白表示時のＹ値は２９．３、黒表示時のＹ値は６．１、コントラストは４．８：１（Ｗ／Ｂ）であり、特に黒表示特性が悪いためコントラストの低い液晶表示素子となってしまった。
（比較実験例３）
ネマティック液晶混合物Ｂ（Δｎ＝０．２１０、Δε＝３８．７、ＴＮ−Ｉ＝１１９℃）に対して、カイラル材料Ｓ−８１１（メルク社製）を２６ｗｔ％添加した液晶組成物Ｂ１を調製した。液晶組成物Ｂ１は５６０ｎｍ付近の波長の光を選択反射するように調製されている。
【００８４】
一方の基板として、透明電極が設けられたガラス基板を用意し、該ガラス基板に設けられた透明電極上に前記化学構造式（１）、（２）、（３）で示される化合物から合成されるポリイミドからなる配向膜を８００Åの厚みで形成し、ナイロン布で一方向にラビングした。
【００８５】
また、もう一方の基板として、透明電極が設けられたガラス基板を用意し、該ガラス基板上の透明電極上には、まず厚み２０００Åの絶縁膜ＨＩＭ３０００（日立化成社製）を形成した後、さらにその上に前記化学構造式（１）、（２）、（３）で示される化合物から合成される、構造中にメソゲン基を有するポリイミドからなる配向膜を８００Åの厚みで形成し、ナイロン布で一方向にラビング処理した。
【００８６】
続いて、一方の基板上の周縁部にシール材ＸＮ２１Ｓ（三井化学社製）をスクリーン印刷して所定高さの壁を形成した。
【００８７】
両基板をラビング方向が平行になるように対向させ、基板間に７μｍ径のスペーサ（積水ファインケミカル社製）を挟んでセルギャップを調整し、前記の液晶組成物Ｂ１を挟持し、これを液晶表示素子とした。
【００８８】
この液晶表示素子の光を入射させる側とは反対側の基板の外面（裏面）に黒色の光吸収体を設けた。
【００８９】
本液晶表示素子を着色状態と消色状態にするために所定電圧（着色時６５Ｖ、５ｍｓ、消色時４０Ｖ、５ｍｓ）で駆動したところ、着色状態における視角依存性が非常に強く、Ｙ値及びコントラストの測定を適切に行なうことはできなかった。
【００９０】
実験結果を以下にまとめて示す。
【００９１】
【表１】
Figure 0004196527
【００９２】
このように、一層の液晶表示素子については、構造中にメソゲン基を有するポリイミドからなる配向膜を有する実験例１の素子ではコントラストが８．６：１と高かった。これに対し、比較実験例１の素子ではコントラストが５．９：１と低かった。なお、実験例１の素子において配向膜をラビング処理した比較実験例３の素子では着色状態における視角依存性が非常に強く、Ｙ値及びコントラストの測定を適切に行なうことはできなかった。
【００９３】
また、液晶表示素子を三層積層した積層型液晶表示素子については、構造中にメソゲン基を有するポリイミドからなる配向膜を有する実験例２〜５の素子ではコントラストが５．８：１〜６．６：１と高かった。これに対し、比較実験例２の素子ではコントラストが４．８：１と低かった。
【００９４】
【発明の効果】
以上説明したように本発明によると、一対の基板間にコレステリック相を示す液晶を含む液晶層が挟持された液晶表示素子であって、前記液晶における液晶分子に均一に配向効果を及ぼすことができ、これにより画像表示におけるコントラストを向上させることができる液晶表示素子を提供することができる。
【００９５】
また本発明によると、一対の基板間にコレステリック相を示す液晶を含む液晶層が挟持された液晶表示素子であって、視角依存性を少なくすることができる液晶表示素子を提供することができる。
【図面の簡単な説明】
【図１】本発明に係る液晶表示素子の１例の概略断面図である。
【図２】本発明に係る液晶表示素子の他の例であり、青色表示を行う液晶層、緑色表示を行う液晶層、赤色表示を行う液晶層の３層の液晶層を含む液晶表示素子の概略断面図である。
【図３】本発明に係る液晶表示素子に設けられる樹脂構造物の配置状態の一例を示す図である。
【図４】本発明に係る液晶表示素子を製造するために一対の基板を貼り合わすための貼り合わせ装置の一例を示す図である。
【符号の説明】
１、２ 一対の基板
３ 光吸収層
４ 柱状構造物
５ スペーサ
６、６ｂ、６ｇ、６ｒ 液晶
７ 絶縁膜
８ 配向膜
１０、１０ｂ、１０ｇ、１０ｒ 液晶層
１１、１２ 透明電極
９１ 平板
９２ 加熱・加圧ローラ
Ｓ シール材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display element.
[0002]
[Prior art]
In recent years, various researches have been made on liquid crystal display elements using a liquid crystal exhibiting a cholesteric phase such as a chiral nematic liquid crystal that exhibits a cholesteric phase at room temperature by adding a chiral material to the nematic liquid crystal.
[0003]
In such a liquid crystal display element, a liquid crystal layer containing a liquid crystal exhibiting a cholesteric phase is usually sandwiched between a pair of substrates. For example, the liquid crystal display element is used as a reflective liquid crystal display element utilizing selective reflection of a liquid crystal exhibiting a cholesteric phase. In this reflective liquid crystal display element, display is performed by switching the liquid crystal between a planar state (colored state) and a focal conic state (decolored state) by applying high and low voltages.
[0004]
The liquid crystal display element may be provided with an alignment film for controlling the alignment of liquid crystal molecules.
[0005]
[Problems to be solved by the invention]
However, in conventional reflective liquid crystal display elements using liquid crystals exhibiting a cholesteric phase, when an alignment film is provided, if the interaction between the liquid crystal and the alignment film is weak, the liquid crystal molecules may have a uniform alignment effect. In the image display, scattering in the focal conic state increases and it is difficult to obtain sufficient contrast.
[0006]
Accordingly, the present invention provides a liquid crystal display element in which a liquid crystal layer containing a liquid crystal exhibiting a cholesteric phase is sandwiched between a pair of substrates, and can uniformly exert an alignment effect on the liquid crystal molecules in the liquid crystal. It is an object of the present invention to provide a liquid crystal display element capable of improving the contrast in the above.
[0007]
Another object of the present invention is to provide a liquid crystal display element in which a liquid crystal layer including a liquid crystal exhibiting a cholesteric phase is sandwiched between a pair of substrates, and the viewing angle dependency can be reduced. .
[0008]
[Means for Solving the Problems]
The present inventor has conducted research to solve the above problems, and in a liquid crystal display element in which a liquid crystal layer containing a liquid crystal exhibiting a cholesteric phase is sandwiched between a pair of substrates having an alignment film on at least one side, the alignment film Introducing a mesogenic group, which is a substituent having an intermolecular interaction with liquid crystal molecules in the liquid crystal, to strengthen the interaction between the liquid crystal and the alignment film and uniformly exert an alignment effect on the liquid crystal molecules. It has been found that the scattering in the focal conic state is reduced and the contrast in image display is improved. It has also been found that the viewing angle dependency can be reduced by not rubbing the alignment film.
[0009]
The present invention is based on such findings, and in order to solve the above problems, a liquid crystal display element in which a liquid crystal layer containing a liquid crystal exhibiting a cholesteric phase is sandwiched between a pair of substrates having an alignment film on at least one side,
There is provided a liquid crystal display element, wherein the alignment film is made of polyimide having a mesogen group in the structure and is not rubbed.
[0010]
The mesogenic group in the present invention refers to a substituent having a rigid structure necessary for a molecule to exhibit liquid crystallinity. Examples of the mesogenic group include a cholesterol group, a biphenyl group, and a phenylbenzoate group.
[0011]
The liquid crystal display element according to the present invention can be used as a reflective liquid crystal display element utilizing selective reflection of liquid crystal exhibiting cholesteric properties.
[0012]
When the liquid crystal display element of the present invention is used as a reflective liquid crystal display element, the liquid crystal is switched between a planar state (colored state) and a focal conic state (decolored state) by applying high and low voltages.
[0013]
According to the liquid crystal display element according to the present invention, the alignment film is made of polyimide having a mesogen group in the structure, so that the interaction between the liquid crystal and the alignment film becomes strong, and the liquid crystal molecules in the liquid crystal have a uniform alignment effect. The contrast in the image display can be improved accordingly. Further, since the alignment film is not rubbed, the viewing angle dependency can be reduced.
[0014]
The following can be illustrated as said mesogenic group.
(A) A mesogenic group containing any one of a steroid skeleton, a biphenyl skeleton, and a phenylcyclohexane skeleton.
(B) A side chain of a diamine compound that forms polyimide.
(C) A combination of (a) and (b).
[0015]
Chemical structural formulas of the compounds for synthesizing the alignment film material are shown in (1) to (5).
[0016]
[Chemical 1]
Figure 0004196527
[0017]
Examples of the alignment film include the following films. That is,
(A) A film made of a polyimide having a mesogenic group containing a steroid skeleton in the structure, which is synthesized from compounds represented by chemical structural formulas (1), (2) and (3).
(B) A film made of a polyimide having a mesogenic group containing a biphenyl skeleton in the structure, which is synthesized from compounds represented by chemical structural formulas (1), (2) and (4).
(C) A film made of a polyimide having a mesogenic group containing a phenylcyclohexane skeleton in the structure, which is synthesized from compounds represented by chemical structural formulas (1), (2) and (5).
[0018]
In any case, the liquid crystal exhibiting the cholesteric phase may be a chiral nematic liquid crystal in which a chiral material is added to a nematic liquid crystal. In this case, the content of the chiral material is preferably about 7 wt (wt)% to 50 wt (wt)%, for example.
[0019]
When a chiral nematic liquid crystal in which a chiral material is added to a nematic liquid crystal is used as the liquid crystal exhibiting the cholesteric phase, the chiral nematic liquid crystal controls the selective reflection wavelength by changing the amount of a chiral dopant (chiral material) to be added. There is an advantage that you can. If the amount of the chiral material added is too small, sufficient memory performance (that is, the planar state retention in the planar state after the voltage application is stopped, or the focal conic state in the focal conic region is maintained). If the amount is too large, the cholesteric phase may not be exhibited or solidified at room temperature.
[0020]
In any case, if the thickness of the alignment film is too thin, the alignment of the liquid crystal molecules may not be controlled, and if it is too thick, the drive voltage increases. For example, the thickness of the alignment film is preferably about 100 to 2000 mm.
[0021]
The liquid crystal display element according to the present invention can be formed into a multilayer liquid crystal display element by laminating at least two layers. In this case, two or more color displays can be performed by using liquid crystal display elements that display different colors as at least two layers of liquid crystal display elements. Note that full color display can be performed by employing at least three liquid crystal display elements, a liquid crystal display element that performs blue display, a liquid crystal display element that performs green display, and a liquid crystal display element that performs red display.
[0022]
In any case, in such a stacked liquid crystal display element, adjacent liquid crystal display elements may have a common substrate.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 is a schematic cross-sectional view of an example of a liquid crystal display element according to the present invention. FIG. 2 shows another example of the liquid crystal display element according to the present invention, which is a multilayer liquid crystal including three liquid crystal layers: a liquid crystal layer for blue display, a liquid crystal layer for green display, and a liquid crystal layer for red display. It is a schematic sectional drawing of a display element. In the liquid crystal display elements shown in FIGS. 1 and 2, portions having basically the same configuration and function are denoted by the same reference numerals.
[0025]
In the liquid crystal display element shown in FIG. 1, a liquid crystal layer 10 including a liquid crystal 6 exhibiting a cholesteric phase is sandwiched between a pair of substrates 1 and 2. Further, the liquid crystal display element shown in FIG. 2 includes a liquid crystal layer 10b that performs blue display including the liquid crystal 6b exhibiting a cholesteric phase and a liquid crystal layer that performs green display including the liquid crystal 6g exhibiting a cholesteric phase between the pair of substrates 1 and 2. 10 g of liquid crystal layers 10 r that perform red display including the cholesteric phase liquid crystal 6 r are sandwiched.
[0026]
At least one of the pair of substrates that can be used for the liquid crystal display element of the present invention including the substrates 1 and 2 needs to have translucency. In addition, a visible light absorption layer is provided on the outer surface (back surface) of the substrate opposite to the light incident side, if necessary. Here, both the substrates 1 and 2 have translucency, and in the example of FIG. 1, the back surface (outer surface) of the substrate 2, and in the example of FIG. 2, the outer substrate 2 sandwiching the liquid crystal layer 10 r is sandwiched. A black light absorption layer 3 is provided on the back surface (outer surface).
[0027]
An example of the light-transmitting substrate is a glass substrate. In addition to this glass substrate, a substrate made of a polymer resin, for example, a flexible resin substrate such as polycarbonate, polyethersulfone, polyethylene terephthalate, polyarylate, or the like can be used.
[0028]
The substrates 1 and 2 have transparent electrodes 11 and 12, respectively. Here, the transparent electrodes 11 and 12 are made of ITO.
[0029]
In the liquid crystal display element shown in FIG. 1 and FIG. 2, a plurality of strip-like transparent electrodes 11 and 12 are formed on the surfaces of the transparent substrates 1 and 2 in parallel with each other. The transparent electrodes 11 and 12 are opposed to each other so that the directions thereof are perpendicular to each other, and a region where the transparent electrodes 11 and 12 overlap is a display pixel.
[0030]
In the liquid crystal display elements of the present invention, including the liquid crystal display elements shown in FIGS. 1 and 2, the substrate surface can be prevented from being short-circuited between the electrodes as needed, or the function of improving the reliability of the liquid crystal as a gas barrier layer. An insulating film can be provided. In the liquid crystal display element shown in FIGS. 1 and 2, an insulating film 7 is provided on the transparent electrodes 11 and 12, respectively. An alignment film 8 is provided on the insulating film 7. The alignment film 8 is made of polyimide having a mesogenic group in the structure and is not rubbed. Here, the alignment film 8 is provided on each of the pair of substrates 1 and 2, but may be provided on at least one of the pair of substrates 1 and 2.
[0031]
In addition to the liquid crystal display elements shown in FIGS. 1 and 2, the liquid crystal display elements of the present invention can be provided with a sealing material for sealing the periphery of the elements so that liquid crystals do not leak. Between the substrates 1 and 2 in the illustrated example, a sealing material S for containing the liquid crystals 6, 6 r, 6 g, and 6 b is provided at the peripheral edge of the substrates 1 and 2 outside the display area.
[0032]
As the sealing material, for example, a thermosetting or photo-curing adhesive such as an epoxy resin or an acrylic resin can be used.
[0033]
In the liquid crystal display element of the present invention, including the liquid crystal display element shown in FIGS. 1 and 2, a spacer for uniformly maintaining a gap between the substrates may be provided between the pair of substrates. In the liquid crystal display element shown in FIGS. 1 and 2, a spacer 5 is disposed between the substrates 1 and 2. Examples of the spacer include a sphere made of resin or inorganic oxide.
[0034]
The liquid crystal display elements of the present invention including the liquid crystal display elements shown in FIGS. 1 and 2 may be supported by a plurality of resin structures between a pair of substrates in order to impart strong self-holding property. In the liquid crystal display element of this example, a columnar structure 4 is provided in a display region between the substrates 1 and 2 as shown in FIGS.
[0035]
FIG. 3 is a diagram illustrating an example of an arrangement state of the resin structure 4. As shown in FIG. 3, the resin structure 4 in the display region is, for example, cylindrical, cross-sectional quadrangular prism, or cross-sectional ellipse arranged at regular intervals based on a predetermined arrangement rule such as a lattice arrangement. It can be a dot shape such as a columnar shape.
[0036]
In the liquid crystal display element of FIG. 1, display is performed by switching between a planar state (colored state) and a focal conic state (decolored state, black display state) in each pixel region of the liquid crystal 6 by applying a predetermined voltage.
[0037]
In the liquid crystal display element of FIG. 2, display is performed by switching between a colored state and a decolored state in each pixel region of the liquid crystals 6r, 6g, and 6b by applying a predetermined voltage. In the liquid crystal display element shown in FIG. 2, when the liquid crystals 6r, 6g, and 6b are all colored, a white color is displayed, and when all are decolored, a black color is displayed.
[0038]
According to the liquid crystal display element described above, since the alignment film 8 is made of polyimide having a mesogen group in the structure, the interaction between the liquid crystals 6, 6b, 6g, 6r and the alignment film 8 becomes strong, and the liquid crystals 6, 6b, 6g. , 6r liquid crystal molecules Have a uniform orientation effect on The contrast in the image display can be improved accordingly. Further, since the alignment film 8 is not rubbed, the viewing angle dependency can be reduced.
[0039]
Next, since the performance evaluation experiment of the liquid crystal display element which concerns on this invention was conducted, it demonstrates below with a comparative experiment.
[0040]
In each of the following experimental examples, Δn is a refractive index anisotropy, Δε is a dielectric anisotropy, T NI Is the isotropic phase transition temperature. The contrast was measured by measuring the Y value (luminous reflectance). The Y value was measured using a spectrocolorimeter CM3700d (manufactured by Minolta) having a white light source.
[0041]
The contrast is given by (Y value in the high reflectance state / Y value in the low reflectance state). The liquid crystal display element in each experimental example described below is in a high reflectance state when the liquid crystal display element is in a colored state, and is in a low reflectance state when in a decolored state.
(Experimental example 1)
Nematic liquid crystal mixture B (Δn = 0.210, Δε = 38.7, T NI = 119 ° C.), a liquid crystal composition B1 to which 26 wt% of chiral material S-811 (manufactured by Merck) was added was prepared. The liquid crystal composition B1 is prepared so as to selectively reflect light having a wavelength near 560 nm.
[0042]
As one substrate, a glass substrate provided with a transparent electrode is prepared, and synthesized from the compounds represented by the chemical structural formulas (1), (2), and (3) on the transparent electrode provided on the glass substrate. An alignment film made of polyimide having a mesogenic group in the structure was formed to a thickness of 800 mm.
[0043]
In addition, a glass substrate provided with a transparent electrode is prepared as the other substrate, and an insulating film HIM3000 (manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 2000 mm is first formed on the transparent electrode on the glass substrate. An alignment film made of polyimide having a mesogenic group in the structure synthesized from the compounds represented by the chemical structural formulas (1), (2), and (3) was formed thereon with a thickness of 800 mm.
[0044]
Subsequently, a seal material XN21S (manufactured by Mitsui Chemicals) was screen-printed on the peripheral edge of one substrate to form a wall having a predetermined height.
[0045]
Both substrates were made to face each other, a 7 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sandwiched between the substrates, the cell gap was adjusted, and the liquid crystal composition B1 was sandwiched, which was used as a liquid crystal display element.
[0046]
A black light absorber was provided on the outer surface (back surface) of the substrate opposite to the light incident side of the liquid crystal display element.
[0047]
When this liquid crystal display element is driven at a predetermined voltage (65 V for coloring, 5 ms, 40 V for decoloring, 5 ms) to turn the liquid crystal display element into a colored state and a decolored state, the Y value when green is displayed is 22.4 and when black is displayed. The Y value was 2.6 and the contrast was 8.6: 1. Both the coloring and black display characteristics were good, and the black display characteristics were particularly good, so that a liquid crystal display element with high contrast was obtained.
(Experimental example 2)
Nematic liquid crystal mixture A (Δn = 0.212, Δε = 44, T NI = 103 ° C.), nematic liquid crystal mixture B (Δn = 0.210, Δε = 38.7, T NI = 119 ° C.), nematic liquid crystal mixture C (Δn = 0.214, Δε = 7.6, T NI = 143 ° C.), liquid crystal compositions A1, B1, and C1 were prepared by adding a predetermined amount, that is, 21 wt%, 26 wt%, and 36 wt% of chiral material S-811 (manufactured by Merck). The liquid crystal composition A1 is prepared to selectively reflect light having a wavelength of about 680 nm, the liquid crystal composition B1 of about 560 nm, and the liquid crystal composition C1 of about 480 nm.
[0048]
Next, as one substrate, a film substrate made of three polycarbonates (PC) provided with a transparent electrode is prepared, and the chemical structural formulas (1) and (1) are formed on the transparent electrode provided on each PC film substrate. 2) Aligned films composed of polyimides having mesogenic groups in the structure and synthesized from the compounds shown in (3) are formed with a thickness of 500 mm, and spacers (Sekisui Fine Chemical) having diameters of 9 μm, 7 μm, and 5 μm are formed thereon. Each).
[0049]
In addition, three PC film substrates provided with transparent electrodes are prepared as substrates on the other side, and an insulating film HIM3000 (manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 2000 mm is first formed on the transparent electrodes on each PC film substrate. After forming each, an alignment film made of a polyimide having a mesogenic group in the structure synthesized from the compounds represented by the chemical structural formulas (1), (2), and (3) is formed thereon with a thickness of 500 mm. Formed.
[0050]
Subsequently, a seal material XN21S (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the peripheral edge of each of the substrates to form walls having a predetermined height.
[0051]
Thereafter, liquid crystal compositions A1, B1, and C1 in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material are respectively applied to each of the substrates, and each of the two substrates is applied to the electrode formation surface. Were superposed so as to face each other, and heated while applying pressure from both sides of the substrate pair. For the pressurization and heating, for example, one substrate (1 in the figure) is placed on a flat plate (91 in the figure) using the bonding apparatus shown in FIG. 4, and the other substrate (2 in the figure) is stacked thereon. The heating can be performed between the roller 92 and the flat plate 91 while being heated and pressed by a heating / pressurizing roller (92 in the figure) from the end. In FIG. 4, S and 5 are a seal wall and a spacer, respectively. In this way, two substrates were bonded together and heated at 150 ° C. for 1 hour to prepare liquid crystal cells a1, b1, and c1.
[0052]
These three types of liquid crystal cells were laminated in the order of a1, b1, and c1 to form a liquid crystal display element. A black light absorbing film was provided on the back surface of the liquid crystal display element (the outer surface (back surface) of the liquid crystal cell a1).
[0053]
Predetermined voltages (coloring: 60V 5ms for a1, 65V 5ms for b1, 75V 5ms for c1, 75V 5ms for decoloring: 40V 5ms for a1, b1 Are driven at 40 V 5 ms and c1 is 50 V 5 ms), the Y value of the liquid crystal display element during white display is 28.5, the Y value during black display is 4.3, and the contrast of the liquid crystal display element is 6. The ratio was 6: 1 (W (white) / B (black)), both white and black display characteristics were good, and the liquid crystal display element with high contrast was obtained because the black display characteristics were particularly good.
(Experimental example 3)
Nematic liquid crystal mixture A (Δn = 0.212, Δε = 44, T NI = 103 ° C.), nematic liquid crystal mixture B (Δn = 0.210, Δε = 38.7, T NI = 119 ° C.), nematic liquid crystal mixture C (Δn = 0.214, Δε = 7.6, T NI = 143 ° C.), liquid crystal compositions A1, B1, and C1 were prepared by adding a predetermined amount, that is, 21 wt%, 26 wt%, and 36 wt% of chiral material S-811 (manufactured by Merck). The liquid crystal composition A1 is prepared to selectively reflect light having a wavelength of about 680 nm, the liquid crystal composition B1 of about 560 nm, and the liquid crystal composition C1 of about 480 nm.
[0054]
Next, as one substrate, a film substrate made of three polycarbonates (PC) provided with transparent electrodes is prepared, and the chemical structural formulas (1) and (1) are formed on the transparent electrodes provided on the PC film substrates. 2) and Alignment films composed of polyimides having mesogenic groups in the structure, synthesized from the compounds shown in (4), are formed with a thickness of 800 mm, and spacers having a diameter of 9 μm, 7 μm and 5 μm (Sekisui Fine Chemical) Each).
[0055]
In addition, three PC film substrates provided with transparent electrodes are prepared as substrates on the other side, and an insulating film HIM3000 (manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 2000 mm is first formed on the transparent electrodes on each PC film substrate. After forming each, an alignment film made of a polyimide having a mesogenic group in the structure, synthesized from the compounds represented by the chemical structural formulas (1), (2), and (4), is formed with a thickness of 800 mm. Formed.
[0056]
Subsequently, a seal material XN21S (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the peripheral edge of each of the substrates to form walls having a predetermined height.
[0057]
Thereafter, liquid crystal compositions A1, B1, and C1 in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material are respectively applied to each of the substrates, and bonded in the same manner as in Experimental Example 2. Two substrates were bonded together using an apparatus and heated at 150 ° C. for 1 hour to prepare liquid crystal cells a1, b1, and c1.
[0058]
These three types of liquid crystal cells were laminated in the order of a1, b1, and c1 to form a liquid crystal display element. A black light absorbing film was provided on the back surface of the liquid crystal display element (the outer surface (back surface) of the liquid crystal cell a1).
[0059]
Predetermined voltages (coloring: 60V 5ms for a1, 65V 5ms for b1, 75V 5ms for c1, 75V 5ms for decoloring: 40V 5ms for a1, b1 Were driven at 40 V 5 ms and c1 was 50 V 5 ms), the liquid crystal display element had a Y value of 28.8 for white display, a Y value of 4.8 for black display, and a contrast of 6.0: 1 ( W / B), both white and black display characteristics were good, and particularly black display characteristics were good, so that a liquid crystal display element with high contrast was obtained.
(Experimental example 4)
Nematic liquid crystal mixture D (Δn = 0.204, Δε = 7.4, T NI = 91.7 ° C.), liquid crystal compositions D1, D2, and D3 were prepared by adding a predetermined amount, that is, 22 wt%, 28 wt%, and 48 wt% of chiral material S-811 (manufactured by Merck). The liquid crystal composition D1 is prepared so as to selectively reflect light having a wavelength of around 680 nm, the liquid crystal composition D2 is around 560, and the liquid crystal composition D3 is selectively reflected.
[0060]
Next, as one substrate, a film substrate made of three polycarbonates (PC) provided with transparent electrodes is prepared, and the chemical structural formulas (1) and (1) are formed on the transparent electrodes provided on the PC film substrates. 2) and an alignment film having a mesogen group in the structure made of polyimide synthesized from the compound shown in (3) with a thickness of 1000 mm, and a spacer of 9 μm, 7 μm and 5 μm in diameter (Sekisui Fine Chemical) Each).
[0061]
In addition, three PC film substrates provided with transparent electrodes are prepared as substrates on the other side, and an insulating film HIM3000 (manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 2000 mm is first formed on the transparent electrodes on each PC film substrate. After forming each, an alignment film composed of a polyimide having a mesogenic group in the structure synthesized from the compounds represented by the chemical structural formulas (1), (2), and (3) is formed thereon with a thickness of 1000 mm. Formed.
[0062]
Subsequently, a seal material XN21S (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the peripheral edge of each of the substrates to form walls having a predetermined height.
[0063]
Thereafter, liquid crystal compositions D1, D2, and D3 in amounts calculated from the height of the sealing material and the area of the portion surrounded by the sealing material are respectively applied to each of the substrates, and bonded in the same manner as in Experimental Example 2. Two substrates were bonded together using an apparatus and heated at 150 ° C. for 1 hour to prepare liquid crystal cells d1, d2, and d3.
[0064]
These three types of liquid crystal cells were stacked in the order of d1, d2, and d3, and this was used as a liquid crystal display element. A black light absorbing film was provided on the back surface of the liquid crystal display element (the outer surface (back surface) of the liquid crystal cell d1).
[0065]
Predetermined voltage (coloring: 105V 5ms for d1, 85V 5ms for d2, 60V 5ms for d3, 60V 5ms for d1, 60V 5ms for d1, and d2 to turn each liquid crystal cell into a colored state and a decolored state Are driven at 50 V 5 ms and d3 is 35 V 5 ms), the liquid crystal display element has a Y value of 27.9 when displaying white, a Y value of 4.4 when displaying black, and a contrast of 6.3: 1 ( W / B), both white and black display characteristics were good, and particularly black display characteristics were good, so that a liquid crystal display element with high contrast was obtained.
(Experimental example 5)
Nematic liquid crystal mixture D (Δn = 0.204, Δε = 7.4, T NI = 91.7 ° C.), liquid crystal compositions D1, D2, and D3 were prepared by adding a predetermined amount, that is, 22 wt%, 28 wt%, and 48 wt% of chiral material S-811 (manufactured by Merck). The liquid crystal composition D1 is prepared so as to selectively reflect light having a wavelength of around 680 nm, the liquid crystal composition D2 is around 560, and the liquid crystal composition D3 is selectively reflected.
[0066]
Next, as one substrate, a film substrate made of three polycarbonates (PC) provided with transparent electrodes is prepared, and the chemical structural formulas (1) and (1) are formed on the transparent electrodes provided on the PC film substrates. 2) The alignment film having a mesogen group in the structure made of polyimide synthesized from the compound shown in (5) is formed with a thickness of 300 mm, and a spacer of 9 μm, 7 μm, 5 μm in diameter (Sekisui Fine Chemical) Each).
[0067]
In addition, three PC film substrates provided with transparent electrodes are prepared as substrates on the other side, and an insulating film HIM3000 (manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 2000 mm is first formed on the transparent electrodes on each PC film substrate. After each formation, an alignment film having a mesogenic group in the structure made of polyimide synthesized from the compounds represented by the chemical structural formulas (1), (2), and (5) is formed on the substrate with a thickness of 300 mm. Formed.
[0068]
Subsequently, a seal material XN21S (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the peripheral edge of each of the substrates to form walls having a predetermined height.
[0069]
Thereafter, liquid crystal compositions D1, D2, and D3 in amounts calculated from the height of the sealing material and the area of the portion surrounded by the sealing material are respectively applied to each of the substrates, and bonded in the same manner as in Experimental Example 2. Two substrates were bonded together using an apparatus and heated at 150 ° C. for 1 hour to prepare liquid crystal cells d1, d2, and d3.
[0070]
These three types of liquid crystal cells were stacked in the order of D1, D2, and D3 to form a liquid crystal display element. A black light absorbing film was provided on the back surface of the liquid crystal display element (the outer surface (back surface) of the liquid crystal cell d1).
[0071]
Predetermined voltage (coloring: 105V 5ms for d1, 85V 5ms for d2, 60V 5ms for d3, 60V 5ms for d1, 60V 5ms for d1, and d2 to turn each liquid crystal cell into a colored state and a decolored state Are driven at 50 V 5 ms and d3 is 35 V 5 ms), the liquid crystal display element has a Y value of 27.4 for white display, a Y value of 4.7 for black display, and a contrast of 5.8: 1 ( W / B), both white and black display characteristics were good, and particularly black display characteristics were good, so that a liquid crystal display element with high contrast was obtained.
(Comparative Experimental Example 1)
Nematic liquid crystal mixture B (Δn = 0.210, Δε = 38.7, T NI = 119 ° C.), a liquid crystal composition B1 to which 26 wt% of chiral material S-811 (manufactured by Merck) was added was prepared. The liquid crystal composition B1 is prepared so as to selectively reflect light having a wavelength near 560 nm.
[0072]
As one substrate, a glass substrate provided with a transparent electrode is prepared, and made of polyimide synthesized from the compounds represented by the chemical structural formulas (1) and (2) on the transparent electrode provided on the glass substrate. The alignment film was formed with a thickness of 800 mm.
[0073]
In addition, a glass substrate provided with a transparent electrode is prepared as the other substrate, and an insulating film HIM3000 (manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 2000 mm is first formed on the transparent electrode on the glass substrate. An alignment film made of polyimide synthesized from the compounds represented by the chemical structural formulas (1) and (2) was formed thereon with a thickness of 800 mm.
[0074]
Subsequently, a seal material XN21S (manufactured by Mitsui Chemicals) was screen-printed on the peripheral edge of one substrate to form a wall having a predetermined height.
[0075]
Both substrates were made to face each other, a 7 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sandwiched between the substrates, the cell gap was adjusted, and the liquid crystal composition B1 was sandwiched, which was used as a liquid crystal display element.
[0076]
A black light absorber was provided on the outer surface (back surface) of the substrate opposite to the light incident side of the liquid crystal display element.
[0077]
When this liquid crystal display element is driven at a predetermined voltage (65 V for coloring, 5 ms, 40 V for decoloring, 5 ms) to turn the liquid crystal display element into a colored state and a decolored state, the Y value when displaying green is 22.6 and when displaying black Has a Y value of 3.8 and a contrast of 5.9: 1, and the liquid crystal display element has a low contrast because of particularly poor black display characteristics.
(Comparative Experiment Example 2)
Nematic liquid crystal mixture A (Δn = 0.212, Δε = 44, T NI = 103 ° C.), nematic liquid crystal mixture B (Δn = 0.210, Δε = 38.7, T NI = 119 ° C.), nematic liquid crystal mixture C (Δn = 0.214, Δε = 7.6, T NI = 143 ° C.), liquid crystal compositions A1, B1, and C1 were prepared by adding a predetermined amount, that is, 21 wt%, 26 wt%, and 36 wt% of chiral material S-811 (manufactured by Merck). The liquid crystal composition A1 is prepared to selectively reflect light having a wavelength of about 680 nm, the liquid crystal composition B1 of about 560 nm, and the liquid crystal composition C1 of about 480 nm.
[0078]
Next, as one substrate, a film substrate made of three polycarbonates (PC) provided with transparent electrodes is prepared, and the chemical structural formulas (1) and (1) are formed on the transparent electrodes provided on the PC film substrates. An alignment film made of polyimide synthesized from the compound shown in 2) was formed with a thickness of 800 mm, and spacers (manufactured by Sekisui Fine Chemical Co., Ltd.) having diameters of 9 μm, 7 μm, and 5 μm were sprayed thereon.
[0079]
In addition, three PC film substrates provided with transparent electrodes are prepared as substrates on the other side, and an insulating film HIM3000 (manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 2000 mm is first formed on the transparent electrodes on each PC film substrate. After each formation, an alignment film made of polyimide synthesized from the compounds represented by the chemical structural formulas (1) and (2) was formed thereon with a thickness of 800 mm.
[0080]
Subsequently, a seal material XN21S (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the peripheral edge of each of the substrates to form walls having a predetermined height.
[0081]
Thereafter, liquid crystal compositions A1, B1, and C1 in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material are respectively applied to each of the substrates, and bonded in the same manner as in Experimental Example 2. Two substrates were bonded together using an apparatus and heated at 150 ° C. for 1 hour to prepare liquid crystal cells a1, b1, and c1.
[0082]
These three types of liquid crystal cells were laminated in the order of a1, b1, and c1 to form a liquid crystal display element. A black light absorbing film was provided on the back surface of the liquid crystal display element (the outer surface (back surface) of the liquid crystal cell a1).
[0083]
Predetermined voltages (coloring: 60V 5ms for a1, 65V 5ms for b1, 75V 5ms for c1, 75V 5ms for decoloring: 40V 5ms for a1, b1 Were driven at 40 V 5 ms and c1 was 50 V 5 ms), the liquid crystal display element had a Y value of 29.3 for white display, a Y value of 6.1 for black display, and a contrast of 4.8: 1 ( W / B) and the liquid crystal display element has a low contrast because of particularly poor black display characteristics.
(Comparative Experiment 3)
Nematic liquid crystal mixture B (Δn = 0.210, Δε = 38.7, T NI = 119 ° C.), a liquid crystal composition B1 to which 26 wt% of chiral material S-811 (manufactured by Merck) was added was prepared. The liquid crystal composition B1 is prepared so as to selectively reflect light having a wavelength near 560 nm.
[0084]
As one substrate, a glass substrate provided with a transparent electrode is prepared, and synthesized from the compounds represented by the chemical structural formulas (1), (2), and (3) on the transparent electrode provided on the glass substrate. An alignment film made of polyimide was formed to a thickness of 800 mm and rubbed in one direction with a nylon cloth.
[0085]
In addition, a glass substrate provided with a transparent electrode is prepared as the other substrate, and an insulating film HIM3000 (manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 2000 mm is first formed on the transparent electrode on the glass substrate. An alignment film made of polyimide having a mesogenic group in the structure, which is synthesized from the compounds represented by the chemical structural formulas (1), (2), and (3), is formed thereon with a thickness of 800 mm. Rubbed in one direction.
[0086]
Subsequently, a seal material XN21S (manufactured by Mitsui Chemicals) was screen-printed on the peripheral edge of one substrate to form a wall having a predetermined height.
[0087]
Both substrates are opposed so that the rubbing directions are parallel, and a cell gap is adjusted by sandwiching a spacer (made by Sekisui Fine Chemical Co., Ltd.) having a diameter of 7 μm between the substrates, and the liquid crystal composition B1 is sandwiched between them. It was set as the element.
[0088]
A black light absorber was provided on the outer surface (back surface) of the substrate opposite to the light incident side of the liquid crystal display element.
[0089]
When this liquid crystal display element is driven at a predetermined voltage (65 V for coloring, 5 ms, 40 V for decoloring, 5 ms) in order to put the liquid crystal display element into a colored state and a decolored state, the viewing angle dependence in the colored state is very strong, Contrast measurement could not be performed properly.
[0090]
The experimental results are summarized below.
[0091]
[Table 1]
Figure 0004196527
[0092]
As described above, the single-layer liquid crystal display element had a high contrast of 8.6: 1 in the element of Experimental Example 1 having the alignment film made of polyimide having a mesogen group in the structure. On the other hand, the contrast of the device of Comparative Experimental Example 1 was as low as 5.9: 1. In addition, in the element of Comparative Example 3 in which the alignment film was rubbed in the element of Experimental Example 1, the viewing angle dependency in the colored state was very strong, and the Y value and contrast could not be measured appropriately.
[0093]
In addition, with respect to the multilayer liquid crystal display element in which three liquid crystal display elements are stacked, the contrast of 5.8: 1 to 6 in the elements of Experimental Examples 2 to 5 having the alignment film made of polyimide having a mesogenic group in the structure. It was as high as 6: 1. On the other hand, the contrast of the device of Comparative Experimental Example 2 was as low as 4.8: 1.
[0094]
【The invention's effect】
As described above, according to the present invention, a liquid crystal display element in which a liquid crystal layer containing a liquid crystal exhibiting a cholesteric phase is sandwiched between a pair of substrates, and the liquid crystal molecules in the liquid crystal can have a uniform alignment effect. Thus, it is possible to provide a liquid crystal display element capable of improving contrast in image display.
[0095]
Further, according to the present invention, it is possible to provide a liquid crystal display element in which a liquid crystal layer including a liquid crystal exhibiting a cholesteric phase is sandwiched between a pair of substrates, and the viewing angle dependency can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an example of a liquid crystal display element according to the present invention.
FIG. 2 is another example of the liquid crystal display element according to the present invention, which is a liquid crystal display element including three liquid crystal layers: a liquid crystal layer for blue display, a liquid crystal layer for green display, and a liquid crystal layer for red display. It is a schematic sectional drawing.
FIG. 3 is a view showing an example of an arrangement state of a resin structure provided in the liquid crystal display element according to the present invention.
FIG. 4 is a view showing an example of a bonding apparatus for bonding a pair of substrates to manufacture a liquid crystal display element according to the present invention.
[Explanation of symbols]
1, 2 pair of substrates
3 Light absorption layer
4 Columnar structures
5 Spacer
6, 6b, 6g, 6r liquid crystal
7 Insulating film
8 Alignment film
10, 10b, 10g, 10r liquid crystal layer
11, 12 Transparent electrode
91 flat plate
92 Heating and pressure roller
S sealing material

Claims (6)

少なくとも一方に配向膜を有する一対の基板間にコレステリック相を示す液晶を含む液晶層が挟持された液晶表示素子であり、
前記配向膜が構造中にメソゲン基を有するポリイミドからなり、且つ、ラビング処理されていないことを特徴とする液晶表示素子。A liquid crystal display element in which a liquid crystal layer containing a liquid crystal exhibiting a cholesteric phase is sandwiched between a pair of substrates having an alignment film on at least one side,
The liquid crystal display element, wherein the alignment film is made of polyimide having a mesogenic group in the structure and is not rubbed. 前記メソゲン基がステロイド骨格、ビフェニル骨格及びフェニルシクロヘキサン骨格のうちのいずれかを含む請求項１記載の液晶表示素子。The liquid crystal display element according to claim 1, wherein the mesogenic group includes any one of a steroid skeleton, a biphenyl skeleton, and a phenylcyclohexane skeleton. 前記メソゲン基がポリイミドを形成するジアミン化合物の側鎖である請求項１又は２記載の液晶表示素子。The liquid crystal display element according to claim 1, wherein the mesogenic group is a side chain of a diamine compound forming polyimide. 前記コレステリック相を示す液晶はネマティック液晶にカイラル材を添加したカイラルネマティック液晶であり、該カイラル材の含有量が７重量％〜５０重量％である請求項１、２又は３記載の液晶表示素子。4. The liquid crystal display element according to claim 1, wherein the liquid crystal exhibiting a cholesteric phase is a chiral nematic liquid crystal in which a chiral material is added to a nematic liquid crystal, and the content of the chiral material is 7 wt% to 50 wt%. 前記配向膜は膜厚が１００Å〜２０００Åである請求項１から４のいずれかに記載の液晶表示素子。The liquid crystal display element according to claim 1, wherein the alignment film has a thickness of 100 to 2000 mm. 請求項１から５のいずれかに記載の液晶表示素子を少なくとも二層積層している積層型液晶表示素子。A multilayer liquid crystal display element comprising at least two layers of the liquid crystal display element according to claim 1.
JP2000237724A 2000-06-30 2000-06-30 Liquid crystal display element Expired - Fee Related JP4196527B2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2000237724A JP4196527B2 (en) 2000-06-30 2000-06-30 Liquid crystal display element
US09/887,654 US6699534B2 (en) 2000-06-30 2001-06-22 Liquid crystal display element

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2000237724A JP4196527B2 (en) 2000-06-30 2000-06-30 Liquid crystal display element

Publications (2)

Publication Number Publication Date
JP2002023168A JP2002023168A (en) 2002-01-23
JP4196527B2 true JP4196527B2 (en) 2008-12-17

Family

ID=18729532

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2000237724A Expired - Fee Related JP4196527B2 (en) 2000-06-30 2000-06-30 Liquid crystal display element

Country Status (2)

Country Link
US (1) US6699534B2 (en)
JP (1) JP4196527B2 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6562420B2 (en) * 2001-07-31 2003-05-13 Industrial Technology Research Institute Liquid crystal aligning film
SE0200910D0 (en) * 2002-03-22 2002-03-22 Ecsibeo Ab A liquid crystal device, a method for producing a liquid crystal device and a method for controlling liquid crystal device
JP5092382B2 (en) * 2006-12-13 2012-12-05 Ｊｎｃ株式会社 Diamine with liquid crystal-like structure
JP2009109770A (en) * 2007-10-30 2009-05-21 Fujitsu Ltd Method of manufacturing display device and display device
JP5099346B2 (en) * 2008-03-25 2012-12-19 Ｊｓｒ株式会社 Liquid crystal aligning agent and liquid crystal display element
TWI362398B (en) * 2009-12-31 2012-04-21 Ind Tech Res Inst Polyimide polymers for flexible electrical device substrate material and flexible electrical devices comprising the same
US8495344B2 (en) * 2010-01-22 2013-07-23 Via Technologies, Inc. Simultaneous execution resumption of multiple processor cores after core state information dump to facilitate debugging via multi-core processor simulator using the state information

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TW290558B (en) 1994-04-28 1996-11-11 Nissan Chemical Ind Ltd
JP3653711B2 (en) 1995-11-28 2005-06-02 Ｊｓｒ株式会社 Liquid crystal alignment agent

Also Published As

Publication number Publication date
US20020006480A1 (en) 2002-01-17
JP2002023168A (en) 2002-01-23
US6699534B2 (en) 2004-03-02

Similar Documents

Publication Publication Date Title
JP3599089B2 (en) Multi-color display
US6565932B2 (en) Liquid crystal composition and liquid crystal light modulating device using the liquid crystal composition
JP4196527B2 (en) Liquid crystal display element
US20020003600A1 (en) Liquid crystal composition and liquid crystal light modulating device
JP2000178557A (en) Liquid crystal composition and liquid crystal light modulation element
JPH1096917A (en) Reflection type liquid crystal display
JP4978391B2 (en) Reflective liquid crystal display medium
JP2002363564A (en) Liquid crystal composition and reflecting liquid crystal display
JP3700756B2 (en) Cholesteric liquid crystal display device
JP3952219B2 (en) Reflective liquid crystal display element
JP4655425B2 (en) Reflective full-color liquid crystal display element and display device including the element
JP3482737B2 (en) Reflective liquid crystal display
US6787201B2 (en) Liquid crystal composition and liquid crystal light modulating apparatus
JP4561003B2 (en) Liquid crystal display element
JP2002107768A (en) Liquid crystal display element
JP4285011B2 (en) Liquid crystal composition and liquid crystal display element
US20010006227A1 (en) Liquid crystal display element
JP2002207225A (en) Liquid crystal display element
JP3758634B2 (en) Liquid crystal display element
JP4378893B2 (en) Liquid crystal display element
JP2007148232A (en) Liquid crystal display element
JP2001147444A (en) Laminated liquid crystal device
JP2001147442A (en) Laminated liquid crystal device
JP2002082356A (en) Liquid crystal display element
JP2003096459A (en) Chiral nematic liquid-crystal composition and liquid crystal display element

Legal Events

Date Code Title Description
A711 Notification of change in applicant

Free format text: JAPANESE INTERMEDIATE CODE: A712

Effective date: 20050613

A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20061025

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20080829

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20080909

A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20080922

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20111010

Year of fee payment: 3

R150 Certificate of patent or registration of utility model

Free format text: JAPANESE INTERMEDIATE CODE: R150

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20111010

Year of fee payment: 3

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20121010

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20121010

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20131010

Year of fee payment: 5

S531 Written request for registration of change of domicile

Free format text: JAPANESE INTERMEDIATE CODE: R313531

S533 Written request for registration of change of name

Free format text: JAPANESE INTERMEDIATE CODE: R313533

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

LAPS Cancellation because of no payment of annual fees